The perimeter of a square is $20$ units. How long is each side?
Explanation: $\text{? }$ The perimeter is the total length of all the sides of the shape added together. $ {\text{?}} + {\text{?}} + {\text{?}} + {\text{?}} = 20\text{ } $ $ {5} + {5} + {5} + {5} = 20\text{ } $ The sides of a square are all the same length, so each side must be $5$ units long.